This invention relates to a bioabsorbable melt spun fiber formed from a glycolide-containing polymer, e.g. a lactide-glycolide copolymer.
Polymers and copolymers of, and bioabsorbable surgical devices made from, lactide and/or glycolide and related compounds are well-known. See, e.g., U.S. Pat. Nos. 2,668,162; 2,703,316; 2,758,987; 3,225,766; 3,297,033; 3,422,181; 3,531,561; 3,565,869; 3,620,218; 3,626,948; 3,636,956; 3,736,646; 3,772,420; 3,773,919; 3,792,010; 3,797,499; 3,839,297; 3,867,190; 3,878,284; 3,982,543; 4,060,089; 4,137,921; 4,157,437; 4,243,775; 4,273,920; and 4,300,565; U.K. patent No. 779,291; D.K. Gilding et al., "Biodegradable polymers for use in surgery-polyglycolic/poly(lactic acid) homo and co-polymers; 1", Polymer, Volume 20, pages 1459-1464 (1979), and D.F. Williams (ed.), Biocompatibility of Clinical Imolant Materials, Vol. II, ch. 9: "Biodegradable Polymers" (1981). Some of these documents disclose copolymers of lactide and glycolide containing fifteen or more mole percent glycolide. See, e.g., U.S. Pat. Nos. 2,668,162; 2,703,316; 3,297,033; 3,620,218; 3,636,956; 3,736,646; 3,773,919; 3,797,499; 3,839,297; 3,867,190; 3,982,543; and 4,273,920 and the Gilding et al. and Williams (ed.) publications.
By way of example, bioabsorbable composite materials intended for use in medical implantation may include reinforcement fibers enveloped in a matrix. Polymers and copolymers of lactide and/or glycolide can be used as the reinforcement fibers or as amorphous fibers to form the matrix. Such a composite material can be molded into a suitable biomedical implant.
Previously, it has not been possible to produce fibrous material from relatively low glycolide copolymer resins (e.g., 15-20 mole percent glycolide content) having acceptable long-term in vivo tensile strength retention. For example, it is disclosed at line 1 of Table VII in Example XVII of U.S. Pat. No. 3,636,956, that a 20/80 mole percent glycolide/lactide copolymer melt spun into monofilaments has a diameter of 15.9 mils and a straight pull of 9.57 pounds, which gives tensile strength of about 48,000 psi. However, line 1 of Table VIII of this patent documents a greater than 50 percent loss in the in vivo tensile strength over a two week period for this filament composition, i.e. from 10.1 pounds at day zero to 4.0 pounds at 15 days post implant.